Magnetic Loops in the Sun's Corona

Magnetic fields can be thought of as lines that connect north and south polarities. On the Earth these lines run from north to south and are uniform and organized. This is why we can navigate so well with a magnetic compass.

On the sun, the magnetic fields connect opposite polarities just as on the Earth. However, while the Earth only has one north and one south pole, on the Sun we observe bits of north and south polarity scattered all over the surface. Furthermore, their position and strengths are constantly changing. The magnetic fields connecting these poles loop out into the corona in a bewildering array of shapes and sizes. They are visible in X-rays because of the hot gas that they trap.

When some of the Sun's magnetic field lines are filled with hot gas, we see a magnetic loop:

Compare this to an actual picture of the Sun from Yohkoh:

Below is a set of 7 pictures illustrating the magnetic loops of the Sun's corona. All of the complex structure seen in these pictures reflect the way the magnetic fields are oriented at that location. The white tick marks in the pictures are each the same length on the Sun, though the image scale varies from picture to picture. The ticks represent a distance of about 43,500 km or 3% the diameter of the Sun. In frames A, B, C, and G you can see the edge, or limb, of the Sun as a dark or bright smooth segment of a circle.

Click to enlarge